JP2006254556A - Stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high quality stepping motor by roughly mathcing the lengths of the magnetic pole of inner yokes and the length of a rotor magnet facing across a specified gap thereby stabilizing its magnetic balance. <P>SOLUTION: In the stepping motor which is equipped axially with a plurality of stators 9 and 10 comprising inner yokes 3 and 4 and outer yokes 7 and 8 having two or more pole teeth arranged alternately in their circumferential directions and exciting coils 5 and 6 installed between these yokes, and is equipped with a rotor magnet 1 which is joined with the inner yokes 3 and 4 and is arranged coaxially inside the stators 9 and 10 via a specified gap from the pole teeth and is magnetized alternately into different poles at its peripheral face, the rotor magnet 1 has a groove of specified depth at its peripheral face opposed to the junction 13 of the inner yoke, and the lengths L1 and L2 of the pole teeth of the inner yokes forming specified gaps G with the rotor magnet and the facing lengths L3 and L4 of the rotor magnet 1 forming specified gaps G with the inner yokes are roughly in accord. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stepping motor having a rotor magnet that rotates in a stator.

In conventional stepping motors, for example, as described in Patent Document 1 or Patent Document 2, a groove portion having a predetermined length / depth is formed in the axial center portion of the circumferential surface of the rotor magnet.
JP 63-198559 A Japanese Patent Laid-Open No. 10-42543

  However, in the above conventional example, the groove portion of the rotor magnet tries to prevent magnetic interference between the plurality of stators. However, the pole tooth length of the inner yoke facing the rotor magnet is different, and therefore, due to the attracting force of the rotor magnet. The balance in the axial direction becomes poor, the rotor magnet is easily displaced from the center position, the magnetic balance is lost, and the effect of preventing magnetic interference between the plurality of stators is reduced / torque is reduced / detent torque is increased / vibrated There has been a problem such as an increase in the number of occurrences.

  The object of the first invention of the present application is to stabilize the magnetic balance by substantially matching the pole tooth length of the inner yoke and the length of the rotor magnet facing each other with a predetermined gap, so that the groove portion of the rotor magnet has a plurality of grooves. An effect of preventing magnetic interference between stators is effective, and a high-quality stepping motor is provided.

  An object of the second invention is to provide a stepping motor that facilitates shape processing and is easy to make.

  In order to achieve the above object, a first invention of the present application comprises an inner yoke and an outer yoke having a plurality of pole teeth alternately arranged in the circumferential direction, and an exciting coil mounted between these yokes. A plurality of stators are provided in the axial direction, the inner yokes are joined, arranged in a coaxial relationship within the stator via pole teeth and a predetermined gap, and alternately magnetized with different poles on the circumferential surface. In a stepping motor provided with a rotor magnet, the rotor magnet has a groove portion with a predetermined depth on the circumferential surface facing the joint portion of the inner yoke, and the pole tooth length of the inner yoke that becomes a predetermined gap and the rotor magnet that becomes a predetermined gap The opposite lengths of these are substantially the same.

  In the above configuration, the pole tooth length of the inner yoke and the length of the rotor magnet facing each other with a predetermined gap are matched to act to stabilize the magnetic balance.

  A second invention of the present application is characterized in that, in the first invention of the present application, the rotor magnet is formed by molding a plastic magnet.

  In the above configuration, the rotor magnet is formed of a plastic magnet so as to facilitate shape processing.

  According to the present invention, the axial balance is achieved by the attracting force of the rotor magnet, the rotor magnet is set at the center position by the attracting force, the magnetic balance is stabilized, and the magnetic interference between the plurality of stators in the groove portion of the rotor magnet is achieved. There is an effect that it is possible to provide a stepping motor that is easy to make with high quality and that can be miniaturized, such as stabilization of the effect of preventing noise / stabilization of torque / reduction of detent torque / reduction of vibration. Further, by molding a plastic magnet, it is possible to provide a stepping motor that can be easily processed and can be miniaturized.

  The best mode for carrying out the present invention will be described below based on examples.

  1 to 6 are drawings that best represent the present invention. FIG. 1 is an exploded perspective view of a first embodiment of the present invention. FIG. 2 is a perspective view of an inner yoke and a rotor magnet of the first embodiment of the present invention. 3 is a side view of the inner yoke and the rotor magnet according to the first embodiment of the present invention, FIG. 4 is a sectional view of the inner yoke and the rotor magnet according to the first embodiment of the present invention, and FIG. 5 is a rotor magnet according to the first embodiment of the present invention. FIG. 6 is a side view of the inner yoke according to the first embodiment of the present invention. In these drawings, 1 is a cylinder alternately magnetized with 10 different poles in the radial direction of the peripheral surface. The shape of the rotor magnet, 1a is a groove having a predetermined depth provided on the peripheral surface of the rotor magnet 1, 2 is a shaft rotatably supported by the bearings 11 and 12, and supports the rotor magnet 1 integrally. Shaft of non-magnetic material such as stainless steel, 3 and 4 are the circumference Inner yokes made of soft magnetic material having a plurality of (five) pole teeth 3a, 4a arranged alternately in the direction, 5 and 6 are between the yokes of the inner yokes 3, 4 and the outer yokes 7, 8. An excitation coil that is mounted to excite the yoke, 7.8 has an outer yoke made of a soft magnetic material having a plurality (five) of pole teeth 7a, 8a arranged alternately in the circumferential direction, Stator made up of inner yokes 3, 4, exciting coils 5, 6 and outer yokes 7, 8, sintered oil-impregnated bearings 11, 12 fixed to the outer yokes 7, 8 by rotatably supporting the shaft 2, 13 Are joints of the inner yokes 3 and 4.

  A plurality of (two) stators 9, 10 are provided in the axial direction, and the inner yokes 3, 4 are joined and arranged at the joint portion 13. The rotor magnet 1 is coaxially arranged in the stators 9 and 10 via the pole teeth 3a and 4a of the inner yokes 3 and 4 and the pole teeth 7a and 8a of the outer yokes 7 and 8 and a predetermined gap G. The groove portion 1a of the rotor magnet 1 is disposed so as to face the joint portion 13 of the inner yoke. The pole teeth 3a and 4a of the inner yokes 3 and 4 form a predetermined gap G with the rotor magnet 1 in the range of the lengths L1 and L2, and the rotor magnet 1 has the pole teeth 3a of the inner yoke in the range of the lengths L3 and L4. , 4a and a predetermined gap G.

  In the above configuration, when the exciting coils 5 and 6 are energized, the yokes of the inner yokes 3 and 4 and the outer yokes 7 and 8 are excited and attracted to the pole teeth 3a, 4a, 7a, and 8a. Torque is generated by repelling and attracting the magnetized magnetic pole, and the rotor magnet 1 is driven to rotate and move in accordance with the energization of the exciting coils 5 and 6, and the driving force is transmitted from the shaft 2 to the outside.

  Here, the groove portion 1a of the magnet is arranged so as to face the joint portion 13 of the inner yoke, and acts to prevent magnetic interference between the plurality of stators. The pole tooth length L1 of the inner yoke that becomes the predetermined gap G and the opposing length L3 of the rotor magnet 1 that becomes the predetermined gap G substantially coincide with each other, and the pole tooth length L2 of the inner yoke that becomes the predetermined gap G and the predetermined gap G Since the opposing length L4 of the rotor magnet 1 is substantially the same, it acts to stabilize the magnetic balance.

  The rotor magnet is formed by molding a plastic magnet and acts to facilitate the shape processing of the groove 1a.

  Alternatively, a sintered magnet may be formed by cutting.

The exploded perspective view of Example 1 of the present invention. The perspective view of the inner yoke and rotor magnet of Example 1 of this invention Side view of inner yoke and rotor magnet of embodiment 1 of the present invention Sectional drawing of the inner yoke and rotor magnet of Example 1 of this invention The side view of the rotor magnet of Example 1 of this invention The side view of the inner yoke of Example 1 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor magnet 1a Rotor magnet groove part 4, 4 Inner yoke 3a, 4a, 7a, 8a Pole teeth 5, 6 Excitation coil 7, 8 Outer yoke 9, 10 Stator 13 Inner yoke joint G Gap C Inner yoke joint Width L1, L2 Pole tooth length L3, L4 of the inner yoke that becomes the predetermined gap G Opposing length of the rotor magnet 1 that becomes the predetermined gap G

Claims (2)

A plurality of stators including inner and outer yokes having a plurality of pole teeth arranged alternately in the circumferential direction and excitation coils mounted between the yokes are provided in the axial direction, and the inner yokes are joined. In a stepping motor provided with a rotor magnet arranged in a coaxial relationship in the stator via a predetermined gap with the pole teeth and alternately magnetized to different poles on the peripheral surface,
The rotor magnet has a groove portion having a predetermined depth on the peripheral surface facing the joint portion of the inner yoke, and the pole tooth length of the inner yoke serving as the predetermined gap and the rotor magnet facing the predetermined gap. A stepping motor characterized in that the lengths are substantially the same.   2. The stepping motor according to claim 1, wherein the rotor magnet is a plastic magnet.

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